D’oh… 1968 felt wide-open, but a reader points out that, of course, the Democratic nominee was Johnson’s VP.

So, let’s see when was the last election with no sitting president or veep as the nominee: 2004 Bush, 2000 Gore, 1996 Clinton, 1992 Bush, 1988 Bush, 1984 Reagan, 1980 Carter, 1976 Ford, 1972 Nixon, 1968 Humphrey, 1964 Johnson, 1960 Nixon, 1956 Eisenhower… there we go, 1952, Eisenhower vs. Stevenson. 

Though maybe that gets an asterisk, since both Truman and his VP, Barkley (then 75), were in the race for awhile.  So: 1948 Truman, 1944 Roosevelt, 1940 Roosevelt, 1936 Roosevelt, 1932 Hoover, 1928… OK, 1924, Hoover vs. Smith.

The next earlier case was the previous election, 1920: Wilson was incapacitated and his VP, Thomas Marshall, wasn’t interested, nor interesting to others.  Apparently Marshall liked to tell a joke about a woman with two sons: one ran away to sea, the other was elected vice president… neither was heard from ever again.